Demand, supply, gap: Transit deserts in Houston

Kyle Shelton | @KyleKShelton | June 9, 2015

 Metro_Sean_Davis

Image: Flickr/ Sean_Davis


A new study suggests that despite METRO's launch of several highly-touted and publicized improvements, the agency is still struggling to address the needs of some communities that depend heavily on transit.

With operations beginning on METRO's two new light rail lines and the reimagined bus system set to begin service in August 2015, the Houston region's transit system is undergoing drastic changes.

There is no denying the merits of these new elements. On the whole, the new rail lines and the streamlinedbus system will benefit many riders. The agency said that its bus system changes will double the number of potential riders who live within a half-mile of a frequent bus route to 1 million people. Meanwhile, the new light rails are providing faster, consistent service to two areas of town with high transit demand.

But, according to researchers at the University of Texas at Austin who have mapped what the changes mean for Houstonians' access to transit, the results of the new systems offer more of a mixed bag.

Junfeng Jiao, an assistant professor of community and regional planning at UT-Austin, and Aaron Nichols, a graduate student in the same department, have studied and mapped the "transit deserts" of major Texas cities.

Their concept is adapted from the more widely-known idea of food deserts, or areas where residents lack access to fresh, nutritious food. By tracking transit deserts,

Jiao and Nichols can highlight the parts of cities that have greater demand for transit than supply.

The researchers released their findings for Austin, Dallas, Fort Worth, Houston, San Antonio in January.

To find out where the gaps in transit service exist, Jiao and Nichols collected two types of information about every census block group in a city: the transit demand and transit supply.

Transit demand is based on the percentage of people in an area that depend on public transit. Researchers arrived at that figure by subtracting the number of cars at a household from the number of eligible drivers living there and extrapolating it across the wider area. From that, the researchers determined the percentage of transit dependent people per acre.

They calculated transit supply by determining the number of transit stops and routes within each block group, as well as the frequency of transit service. They also considered the length of sidewalks, bike routes and low-speed roads as well as the density of intersections. The numbers were aggregated into a transit-supply per acre measurement.

Transit demand was then subtracted from transit supply. If the number is negative, the area is considered a transit desert.

The researchers acknowledge that the approach isn't perfect. The number of cars per household is certainly not the sole factor that determines use of transit. For example, a household of five in which all members are over the age of 16 is unlikely to own five cars. By the study's mechanisms, such a household would be considered transit dependent. In reality, though, this car-to-person gap does not automatically make a household transit dependent. Indeed a household might get along fine with three or even two family vehicles.

METRO itself has questioned the methodology of the study as it relates to Houston. “It’s important to note that while it is clear some of the metrics and values used to rate Houston’s transit gaps do not apply to our service area, METRO welcomes the discussion as it relates to how we can all work to improve transit,” the agency said in an email.

Despite this shortcoming, as a basic measure, the transit gap analysis offers a baseline for isolating transit-needy areas, evaluating existing service and helping planners and policymakers direct future transit investment to places that desperately need it.

Below are maps of what Houston's transit demand, supply, and gaps looked like in the initial study. These maps include the current bus system and the light rail's Red Line, but they do not account for the new rail lines or the redesigned bus network.  

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Image from Jiao and Nichols, UT-SOA, Center for Sustainable Development, "Texas Transit Deserts,"

What jumps out from these maps is that most of Houston was already covered fairly well by METRO prior to the recent changes. While there are many sections of the city classified as transit deserts, especially in the southwestern part of the city, most of the city has a least passable service levels.

The gap map also shows a significant surplus of transit supply to the central city. This stems from the fact that, until the bus reimagining goes into effect, most METRO bus routes connect through downtown as part of a spoke-and-wheel system, creating a huge surplus of supply there. The reimagined network will run fewer buses through the center of the city, better utilizing the existing bus fleet and eliminating such oversaturation by switching to a system that runs on a grid pattern.

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Image from Jiao and Nichols, UT-SOA, Center for Sustainable Development, "Texas Transit Deserts,"

Recently, Jiao and Nichols recreated Houston's maps accounting for the reimagined bus network (though not the new real lines). Here is an updated gap map.

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Image from Jiao and Nichols, UT-SOA, Transit Deserts Houston Reimagining Update

Unsurprisingly, the transit surplus downtown has more or less dissipated as many routes have been redrawn to run independent from a central city hub. The area of the city now covered by adequate service has also grown, due mostly to the fact that changes in the deployment of the bus fleet will mean some routes run more frequently.

Worryingly, though, the city's worst transit gaps persist. The researchers show the areas in Houston that had the largest transit gaps before the reimagining will still be underserved. Sharpstown and Gulfton each have huge transit demand, and according to Jiao and Nichols methodology, will each see dips in future supply because of the changes to current routes.

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Image from Jiao and Nichols, UT-SOA, Transit Deserts Houston Reimagining Update  

Beyond these major pinch points, other parts of the city continue to have significant transit gaps as well. Clearly, the reimagining is not a panacea for Houston's transit provision problems.

Of course, it's naive to expect the reimagining to address all transit problems and meet all transit need in the Houston region. This is the first major retooling of the system in several decades, and METRO did not increase its operating budget to make the changes. Given the outcomes depicted by Jiao and Nichols, the bus reimagining is going to have a huge positive impact on Houstonians' overall mobility.

METRO says the improvements are expected to contribute to a 20 percent increase in ridership within two years. “METRO’s New Bus Network will connect 1 million people to 1 million jobs on the frequent network portion of the system with buses coming every 15 minutes or less.” the agency said in an email. “That’s more than double the number of people and jobs connected on the systems current frequent routes.”

However, the gaps these maps do highlight provide a blueprint for future transit investment. The reimagining is just another step - albeit a huge one - in METRO's ongoing push to improve its service to the region. As the agency tweaks the new network, adds future routes, or expands in other ways, attempting to address persistent transit gaps should be a priority.

Moreover, Jiao and Nichols’ study points to the need for the city and region to improve other elements of its built environment, not just its mass transit. Improving sidewalk infrastructure or adding more bike lanes would also help close transit gaps. The agency said in an email that it’s working with partners to improve everything from bike trails that access bus routes to the streets and sidewalks along its new rail lines. “We will continue to work with city and county partners to enhance the public transit experience,” the agency said.

METRO’s work to improve the region’s overall mobility isn’t done, but neither is that of the city or county.